The present invention relates to a neutron image detecting method for creating one-dimensional or two-dimensional neutron images at a high speed and with increased position accuracy, and relates to a neutron image detector using this method. The present invention can be applied to various purposes for the measurement of intense pulsed neutrons in a high-intensity photon accelerator facility (e.g. J-PARC), the evaluation of various dynamic behaviors in nuclear reactors and fusion reactors, the non-destructive inspection using high permeability of neutrons, and the physical property measurement of new materials.
As for the two-dimensional neutron image detector used for neutron scattering experiments using neutron sources generated by a nuclear reactor or an accelerator, what have been used include such a detector as being formed by combining a neutron scintillator or a fluorescent neutron detecting sheet formed together with a fluorescent material and a neutron convertor with a wavelength shifting fiber (refer to Patent Literatures 1 and 2, and Non-Patent Literature 1). Such two-dimensional image detector is characterized in that the position information is obtained by using a cross-fiber reading method, including proven methods such as a method for determining the incident position by using a coincidence counting method using such a sheet configuration that a couple of wavelength shifting fiber bundles are arranged diagonally on the upper surface and the bottom surface of the fluorescent material sheet or the scintillator plate, a method for determining the incident position by using a coincidence counting method using such a sheet configuration that couple of wavelength shifting fiber bundles are arranged diagonally on the back surface of the scintillator by improving the cross-fiber reading method, and a method using such a sheet configuration that a couple of wavelength shifting fiber bundles are arranged diagonally and that scintillators are arranged on its upper surface and bottom surface.
In relation to the method for determining the incident position of neutrons by using a median point calculating method in the same way as the present invention, what is known as Anger-type camera method uses such a method in that gamma-rays or fluorescent lights from the neutron scintillator are detected directly by a number of photomultiplier tubes, and the incident position is determined by a median point calculating method on the basis of the digitized values of the fluorescent light intensity by using Analog/Digital Converter (hereinafter referred to as ADC) (for example, refer to Patent Literature 3).    [Patent Literature 1] JP 2000-187007 A    [Patent Literature 2] JP 2002-71816 A    [Patent Literature 3] JP 2009-8695 A    [Non-Patent Literature 1] Nucl. Instr. and Meth., A439 (1999) PP. 311-320.